Slice off the top of each loaf of french bread, hollow out the loaf then place folded slices of cheddar cheese inside the bread covering the entire loaf.
Spread out thinly sliced onions into the loaf then remove the casing on the bratwurst and form into an oblong patty. press the patties into the bread so that the entire top of the loaf is covered in a layer of sausage.
Place brat bread meat side down on the grill land don't touch for 15-20 minutes. Flip the bread over and cook for about 10 minutes on the other side until the sausage is cooked to 155 degrees F.
Remove the bread from the grill and slice it into 2-inch sections. Serve with whole grain mustard.
Serving size is about 3 sections of the brat bread